The invention generally relates to robotic and other sortation systems, and relates in particular to robotic and other sortation systems that are intended to be used in dynamic environments requiring the system to accommodate processing a variety of objects.
Many order fulfillment operations achieve high efficiency by employing a process called wave picking. In wave picking, orders are picked from warehouse shelves and placed into bins containing multiple orders that are sorted downstream. At the sorting stage individual articles are identified, and multi-article orders are consolidated into a single bin or shelf location so that they may be packed and then shipped to customers. The process of sorting these articles has been done by hand. A human sorter picks an article from an incoming bin, finds the barcode on the object, scans the barcode with a handheld barcode scanner, determines from the scanned barcode the appropriate bin or shelf location for the article, and then places the article in the so-determined bin or shelf location where all articles for that order are placed.
Manually operated barcode scanners are generally either fixed or handheld systems. With fixed systems, such as those used at point-of-sale systems, the operator holds the article and places it in front of the scanner so that the barcode faces the scanning device's sensors, and the scanner, which scans continuously, decodes any barcodes that it can detect. If the article is not immediately detected, the person holding the article typically needs to vary the position or rotation of the article in front of the fixed scanner, so as to make the barcode more visible to the scanner. For handheld systems, the person operating the scanner looks for the barcode on the article, and then holds the scanner so that the article's barcode is visible to the scanner, and then presses a button on the handheld scanner to initiate a scan of the barcode.
Other ways of identifying items by barcode scanning require that the barcode location be controlled or constrained so that a fixed or robot-held barcode scanner can reliably see the barcode. Automatic barcode scanners also involve either fixed or hand-held systems, and the same principles apply. In the case of barcode scanners typically used in industrial applications, the possible positions of barcodes must be tightly controlled so that the barcodes are visible to the one or more scanners. For example, one or more barcode scanners may be placed in fixed locations relative to a conveyor or series of moving trays so that the scanners may scan objects, typically boxes, as they pass by the scanners. In these installations the range of placement of the barcodes is comparatively limited as they must be on labels affixed to one of four sides or top of a box, which also needs to be presented at orientations suitable for scanning. The detected barcode is then associated with the immediate section of the conveyor or is associated with the particular moving tray in which the object had been placed prior to scanning.
In all of these cases, the systems employ sensors, cameras or laser reflectivity sensors, as well as software to detect barcodes and decode them. These methods have inherent limitations that include the range of distances of orientations relative to the detection system, over which they are able to reliably scan barcodes. Firstly, the barcode must be facing the scanner; secondly the range to the barcode must be such that individual elements can be reliably distinguished; and, thirdly, the tilt and skew of the barcode must be such that individual elements can be reliably distinguished. The types of sensors employed, and the robustness of the software detection and decoding schemes determine these performance parameters. There remains a need, therefore, for an object identification system for a robotic system that is able to accommodate the automated identification and processing of a variety of objects in a variety of orientations.